The invention relates to improvements in making filter rod sections for use in machines for the production of filter cigarettes or other filter tipped rod-shaped products of the tobacco processing industry. More particularly, the invention relates to improvements in methods of and in apparatus for making composite filter rod sections which can be utilized as tobacco filtering portions of filter cigarettes and the like.
It is already known to make filter rod sections from a continuous strand (normally called tow) of fibrous filter material (such as acetate fibers) which is drawn from a source of supply (normally in the form of a bale of highly compacted tow) and is thereupon subjected to a number of treatments (including spreading, stretching, sprinkling with a softening agent and condensing) prior to draping into a continuous web of wrapping material (such as imitation cork or cigarette paper). The thus obtained filter rod is thereupon subdivided into sections of desired length, and such sections are transported to storage or into a tipping machine, e.g., into a filter tipping machine wherein filter rod sections of unit length or multiple unit length are connected with plain cigarettes of selected length.
It is also known to contact the running tow of fibrous filter material with another filtering component in order to enhance the desirable characteristics of the resulting filter rod sections. A presently preferred filtering component which is added to successive increments of the running tow of acetate fibers or other filamentary filter material is activated carbon which is admitted in granular or pulverulent state. Reference may be had, for example, to commonly owned published German patent application No. 38 23 707 of Wolfgang Steiniger et al. The thus obtained so-called charcoal filters have been found to be highly satisfactory in that they can intercept high percentages of tar and nicotine from tobacco smoke which flows from the lighted end of a filter cigarette or a like smoker's product to the mouth of the smoker. The published German patent application of Steiniger et al. proposes to add metered quantities of activated carbon to successive increments of the running tow downstream of the last tow treating station and immediately ahead of the wrapping mechanism wherein the tow (which carries particles of activated carbon) and wrapping material are converted into a continuous filter rod which is ready to pass through a so-called cutoff in order to be subdivided into filter rod sections of desired length.